CCTV camera switch box

[Wp100]

Hi,

Wanting to manually switch the DVR recorder video input channel between two cameras, but apart from the BNC connectors and a simple switch is anything else needed ?

The few such devices on the usual sites seem very expensive, wondered if they use / need extra electronics ?

 

[Nigel Goodwin]

No, that's all you need - there will probably be a glitch when you switch, but it shouldn't be of any consequence.

 

[gophert]

BNC connector on a DVR? Is it a commercial/lab unit?

 

[Nigel Goodwin]

BNC connector on a DVR? Is it a commercial/lab unit?

Presumably he means a CCTV DVR?, as they commonly use BNC sockets.

So I suppose they are commercial rather than domestic?.

 

[JimB]

The few such devices on the usual sites seem very expensive, wondered if they use / need extra electronics ?

There is probably some electronics in there to sort out the sync pulses in order to avoid...

there will probably be a glitch when you switch,

the glitch mentioned by Nigel.

But if you can live with the glitch, keep it simple.

JimB

 

[Wp100]

Thanks, yes it is a 4 channel 2mp cctv dvr with RG59 cabling.

Just want to be able to use a different camera on one channel occassionally, but was not sure if a simple switch would cause any impedance problems etc.

Could upgrade to a similar 8 channel 2 mp dvr but seems the recording frame rate is reduce to 12fps from the current 25fps; not worth uppgrading to a more expensive unit.

 

[JimB]

was not sure if a simple switch would cause any impedance problems

If you want to be pernickety, yes it will cause an impedance bump.
But if you keep the wires to the switch as coax or a loosely twisted pair, I don't think that you will have any problems.

JimB

 

[Nigel Goodwin]

If you want to be pernickety, yes it will cause an impedance bump.
But if you keep the wires to the switch as coax or a loosely twisted pair, I don't think that you will have any problems.

That's mainly a theoretical 'issue' and not a problem in reality - the frequencies in use are really quite low - and a LOT of cameras are even connected VERY nastily using telephone or alarm wire with little detriment.

Personally I often used CAT5 cable, with BNC to CAT5 baluns at either end (rather nicer than using just the wires) and that works extremely well over long distances - it was particularly convenient where I used to work because I ran a number of CAT5 cables to plug boards during building work, seeing as I couldn't get any sense from those responsible during the actual work. I just KNEW when it was all done they were going to expect me to go back and wire it all - so the CAT5 cables gave me lot's of plugable options, and was trivial to fit during the building work.

I ran all the phone system down it, the CCTV system (in both directions, including multiple cameras and multiple outputs, including two DVR's) - plus of course Internet and networking.

The CCTV baluns were great for this - as they had four BNC's, to plug the cameras in (or out to the DVR), plus screw terminals for the wires, and a CAT5 socket you could use. So just a short CAT5 cable from balun to plugboard, and the same the other end. If you're not running four cameras you can even use the spare wires for feeding power (12V) to power the cameras.

 

[Wp100]

As we did not know any better we just used RG59 shotgun cable for our simple rewire.

Out of interest is there any difference bewteen these various baluns other than input connectors, seem to vary in price, though all saying Passive type.
This pdf of the simple and cheapest type suggest 10mtrs max distance , yet others up to 450m ?

https://www.farnell.com/datasheets/1965169.pdf

 

[Nigel Goodwin]

As we did not know any better we just used RG59 shotgun cable for our simple rewire.

Nothing wrong with coax, but it's a lot more expensive, and you can only run one camera down each core, so two cameras with shotgun - and of course it's a lot more visually intrusive.

[/QUOTE]

These are the sort of things I used:

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Easy to use and work great - I used quite a few of them, along with video amplifier/splitters, to feed multiple monitors at various locations, as well as feeding the cameras. I even used one ethernet cable for sending two cameras down to a DVR, and two vido signals back up the same cable to feed two monitors with pictures from two different DVR's